In order to provide the rotation function, doors and windows are usually connected to the objects (e.g. cabinets or doorframes) through the hinges. However, the conventional hinge is employed to provide the rotation function merely, but fails to position the door and the window relative to the object effectively at a specific angle. For some doors and windows implemented in a specific environment and frequently needing to be rotated upwardly and downwardly, the hinges employed to position the doors and windows have to provide enough torsional frictions, so that the doors and windows can be opened and kept at specific positioning angles. Consequently, the positioning hinges are developed to meet the requirements of the market.
Nowadays, the positioning hinge on the market is constructed by a friction damping piece, which is fitted in a hinge sleeve to rub against the circular shaft therein. Thus, the door and window can be opened and kept at a specific positioning angle by the torsional friction generated between the friction damping piece and the circular shaft. For generating the torsional friction between the friction damping piece and the circular shaft, the inner diameter of the friction damping piece is designed to be slightly smaller than the outer diameter of the circular shaft before being assembled. Since the friction damping piece has to be fitted in the hinge sleeve, it is not easy to assemble the positioning hinge and the frictional torque between the circular shaft and the corresponding hinge sleeve fails to be controlled or adjusted easily. Moreover, the torsional friction provided by the positioning hinge is limited by the structure and materials of the positioning hinge. Consequently, the positioning hinge fails to meet the practical requirement while a positioning hinge with high torsional friction is required for keeping the doors or windows at a required positioning angle in a specific environment.
Therefore, there is a need of providing an adjustable positioning hinge with high torsional friction and an assembling method thereof to meet the above requirements and solve the above problems.